High porosity abrasive articles and methods of manufacturing same

The present application claims priority from U.S. Provisional Patent Application No. 61/046,134, filed Apr. 18, 2008, entitled “HIGH POROSITY ABRASIVE ARTICLES AND METHODS OF MANUFACTURING SAME,” naming inventors Rachana Upadhyay and Richard Hall, which application is incorporated by reference herein in its entirety.

This disclosure, in general, relates to high porosity abrasive articles and methods for making such high porosity abrasive articles.

Abrasive articles are used in various industries to machine work pieces, such as by lapping, abrading, or polishing. Machining utilizing abrasive articles spans a wide industrial scope from the optics industry, the automotive body repair industry, to the semiconductor fabrication industry. In each of these examples, abrasives are used to remove bulk material or affect surface characteristics of products or work pieces.

In a particular example, the semiconductor industry uses abrasive articles to remove bulk material from the backside of a semiconductor wafer, known as backgrinding. Backgrinding often includes multiple machining steps, including a coarse grind to effect bulk material removal, followed by one or more fine grind steps to reduce subsurface damage, and provide a smooth surface finish that may be within a range of 50 to 500 Angstroms, for example. Such processing is believed to result in more consistent electrical properties in the substrate of the circuits printed on the front side of the semiconductor wafer. Moreover, with the advent of technologies that rely on the formation of electrical connections through the wafer, backside planarization, bulk material removal, and surface quality are becoming increasingly important.

However, the bulk material removal rate and the surface quality of the backside of the semiconductor wafer are notably dependent on not only the grit size of the abrasive article used in machining, but also on structure of the abrasive article. In particular, abrasive articles that trap dislodged abrasive grains and swarf between the abrasive article and the wafer often cause scratching in the surface of the wafer. As such, the surface quality on the backside of the wafer is poor following abrasion, which may influence the electrical properties and the circuitries formed on the front side of the wafer.

As such, an improved abrasive article would be desirable.

In a particular embodiment, an abrasive article includes a polymer matrix and abrasive grains dispersed in the polymer matrix. The polymer matrix is polymerized from a monomer including at least one double bond. The abrasive article has a void volume of at least 50%, such as at least 65%. In a particular example, the abrasive grains have an average particle size of 0.1 μm to 100 μm, such as 0.1 μm to 10 μm. In another particular example, the abrasive grains are selected from the group consisting of silica, alumina, zirconia, zirconia/alumina oxides, silicon carbide, garnet, diamond, cubic boron nitride, silicon nitride, ceria, titanium dioxide, titanium diboride, boron carbide, tin oxide, tungsten carbide, titanium carbide, iron oxide, chromia, flint, and emery. For example, the abrasive grains may be superabrasive grains selected from the group consisting of cubic boron nitride, hard carbonaceous materials and a mixture thereof. In a further example, the abrasive grains have a Mohs hardness of at least 8. In a particular example, the abrasive article includes greater than 10 wt % of the abrasive grains. In another particular example, the abrasive article includes 2 vol % to 30 vol % of the abrasive grains. In an exemplary case, the polymer matrix includes a polymer formed of a monomer selected from the group consisting of vinyl, acrylate, methacrylate, conjugated diolefin, allene, and olefin halide monomers. In another example, the polymer matrix has an open cell structure, such as an open cell structure having a pore and throat configuration. Further, the abrasive article may have a surface area of at least 2.0 m²/g, such as at least 3.0 m²/g.

In another exemplary embodiment, a method of forming an abrasive article includes combining polymeric precursors and abrasive grains to form a first liquid component, forming an emulsion from the first liquid component and a second liquid component, and curing the polymeric precursors of the first liquid component. The second liquid component is substantially immiscible with the first liquid component. The polymer precursors include a monomer including at least one double bond. In an example, combining the polymer precursors and the abrasive grains includes combining an emulsifier with the polymer precursors and the abrasive grains. In an additional example, combining the polymer precursors and the abrasive grains includes combining a stabilizing agent. In a particular example, curing comprises exposing the emulsion to actinic radiation or thermal energy. In another particular example, forming the emulsion includes forming the emulsion with at least 65 vol % of the second liquid component. In an additional example, the method further includes treating the abrasive grains with a coupling agent. In a particular example, the coupling agent is hydrophobic. In a further particular example, the polymer precursors are thermally curable. In another particular example, the polymer precursors are polymerizable through free radical polymerization. In particular, the first liquid component may be hydrophobic. In an example, combining the polymer precursors and the abrasive grains includes combining at least 10 wt % of the abrasive grains. In a further example, the abrasive grains have an average particle size of 0.5 μm to 6 μm.

In an additional exemplary embodiment, a method of polishing an article includes applying an abrasive article to the surface of the article and abrading the surface of the article. The abrasive article includes a polymer matrix and abrasive grains dispersed in the polymer matrix. The polymer matrix is polymerized from a monomer including at least one double bond. The abrasive article has a void volume of at least 50 vol %, such as at least 65 vol %. In an example, the abrasive article includes greater than 10 wt % of the abrasive grains.